I received my cooker and have made some interesting and delicious meals with it. Below are my impressions.
The immersion heater itself works, and is accurate. Measuring with four other thermometers (one of them a high-precision digital one), temperature readings were accurate to 0.3 C.
Problem with the unit itself: it stinks. Literally. The instant I opened the box, the room filled with an acrid smell, reminiscent of burning plastic or overheating electrical insulation. This wasn't just a strong smell; it was a smell that filled the house. The smell comes from the rubberised covering on the handle. That's a nice grippy surface that looks good, but smells terrible. I've kept the unit outside in the sun for the past two weeks. It's still too smelly to take back inside. (And, no, I'm not fuzzy about things that smell a little.)
The clear/transparent plastic cap that is supposed to be removable at the bottom of the unit cannot be removed. (No, I'm am not trying to turn it in the wrong direction.) No matter how hard I grip (with towel and without), it will not budge. (Yes, I watched the support video of how to do it. The cap will not move, period.) If I were to try any harder, I'd have to use pliers, and would possibly break the cap or bend the tube, which I don't want to risk.
The iPhone app is unreliable. Pairing was easy and worked on the first attempt. But the bluetooth connectivity is dodgy. If the phone goes to sleep and wakes up later, the app frequently can't re-establish communication with the cooker. Sometimes, killing the app and re-starting it fixes that problem. Other times, it doesn't. On the up-side, the connectivity loss doesn't affect the settings on the cooker, so it keeps maintaining temperature and the timer. On the down-side, it makes the app useless if this happens (and it happens often). To get the app to talk to the device again, you have to power-cycle the device.
On one occasion, the app decided that cooking was done and started beeping after about 3 hours into a 48-hour timer setting. It simply decided that it was time to stop the cooker. No idea why. My phone was just sitting there doing nothing special when the app beeped and told me that cooking was done. I ended up subtracting the elapsed time from the total cooking time, reset the timer and basically restarted the whole thing, which got me to my desired 48 hours of cooking.
Overall, I'm disappointed. The Anova is a nice device, but with lots of hastily put-together things that should have been left out. The iPhone app (I didn't try the Android one) doesn't work reliably enough. Manually operating the device without the app (if I can manage to find out how, because it's not documented) would be preferable to an app that doesn't work some of the time.
The stuck plastic cap is annoying. I can remove the entire stainless steel tube for cleaning, but I cannot remove the plastic cap to get into the tube from both ends and for cleaning the cap itself.
The stink of the plastic on the cooker is extreme. I expect that it will eventually dissipate but, until it does, it's not possible to keep the unit inside without everyone who walks into a (large) open space immediately commenting on whether you have something burning. (I had four separate people say exactly that.)
So, yes, it works. I've cooked some nice sous vide with it (outside). The app sucks, the plastic stinks, the documentation for how to operate the thing without the app is practically non-existent, and the stuck cap indicates poor quality control.
It's an average device that does an average (and not very complicated job). I'll keep it, because I can make it work and live with the flaws. But I expected better.